Spark ignitor loading and releasing apparatus



United States Patent 3,307,053 SPARK IGNITOR LOADING AND RELEASING APPARATUS Benedictus Furth, Zandvoort, Netherlands, assignor to Honeywell G.m.b.H., Frankfurt am Main, Germany, a corporation of Germany Filed Apr. 30, 1964, Ser. No. 363,694 Claims priority, application Germany, Nov. 20, 1963, H 50,893 4 Claims. (Cl. 310-8) The present invention deals with piezoelectric ignitors for gas burners, such ignitors having a piezoelectric crystal to be impacted by a spring biased hammer. Specifically, the invention provides an ignitor with an improved lever arrangement for loading and releasing the impacting mechanism.

It is an object of the invention to provide a piezoelectric ignitor with an impacting mechanism which is simple and sturdy and which after every operation automatically resets to its starting position. According to the invention, this object is accomplished by means of a pivoted lever which has a short arm engaging a hammer which is to be loaded. The lever is spring loaded and includes an elongated hole for the lever pivot axle. A stop is fixed to the housing and is engaged by the lever after pivoting of the lever through a predetermined angle. When further force is applied to the lever, the lever pivots around the point of engagement between the stop and the lever, with the lever moving with respect to the pivot axle along the elongated hole. The short arm of the lever will then come out of engagement with the loaded hammer.

With such an arrangement, a trigger-slack can be felt when the stop-area of the lever engages the stop fixed to the housing. At this moment the spring loading action is finished and every additional force applied to the lever releases the hammer to eifect impact of the crystal and an ignition spark. It is desirable that the stop-area of the lever and the stop which is fixed to the housing have a different radius of curvature. For instance, one of the areas to be engaged may be plain, or both may be convex, or one may be convex and the other may be concave. In the last mentioned case the radius of curvature of the convex area must be smaller than the radius of the con-cave area.

According to the preferable embodiment of the invention, the reset spring for the lever surrounds the axle of the lever and is fixed with its one end attached to the lever and with the other end attached to the housing or to a mounting assembly. This reset spring operates in such a manner that after releasing the lever, the backward movement of the lever is caused by this spring about the stop fixed to the housing as well as about the fixed axle of the lever. The hammer may move in straight or in turning direction, or may follow a combination of such movements.

Producing the spring load for the hammer can be provided by different kinds of springs. According to a preferred embodiment of the invention, the hammer is carried by two spring blades, the areas of which are parallel to each other, with one end of each fixed to the housing. The space between the spring blades is then used for mounting the loading and releasing mechanism. The two spring blades may also be the free legs of a -shaped single spring whose cross member is fixed to the housing or a mounting plate of the ignitor. Such a U-shaped spring is then the bearing and guiding member for the hammer, and also is the loading spring and the mounting device for the hammer as well as the spring elements.

i More details will be explained by the following description of an example shown in the drawings. In the drawingsz FIGURE 1 shows a cross section of the new device,

FIGURE 2 is a side view of FIGURE 1 whereat the right spring blade 4 and the housing in the area surrounding the axle 13 are broken away, and

FIGURE 3 is a view of the device of FIGURE 1, viewed from below.

Fixed t0 the bottom of the housing 1 is a middle cross member 2 of a U-shaped spring blade. The hammer 5 is mounted between the free legs 3 and 4 of the spring blade. The hammer includes a groove 6 with an edge or drive ridge 7. The short arm 8 of the lever 9 engages the edge 7. The lever 9, for example, consists of artificial resin and has a metallic piece 11 attached to the short arm 8. Piece 11 acts as a drive means or dog cooperable with edge 7.

The long arm 12 of the lever acts as a handle or actuating means and is arranged to be manuallly turned in a clockwise direction. When so turning, the lever is pivoting about the axle 13 which is fixed to the housing and hammer 5 is moved to the right to load the spring arrangement 3, 4. As soon as the stop area or surface 14 of the lever 9 engages the stop 15 which is part of the housing, the spring loading process as mentioned above is limited. Now the spring blades 3 and 4 are fully loaded.

If additional force is now supplied to the long arm 12 of the lever 9, this lever will turn about the contact point between the surface 14 and the stop 15. During this movement, the elongated hole 16 of the lever is moved downward with respect to the axle 13. In continuation of this procedure, the piece 11 disengages the edge 7 of the hammer so that the hammer suddenly moves to the left under the influence of the loaded spring blades 3 and 4. The hammer, with its impact member 21, strikes on the impact plate 22 which transfers the impact force to the piezoelectric crystal 23. Because of this sudden pressure which is applied to the crystal, electrical charges are created on the two face areas of the crystal and are used for producing a high voltage spark in an outer electrical circuit. For this purpose, an ignition cable can be connected to the ignition pin 25, which pin is electrically connected to the bearing disc 24. The electrodes of the crystal are provided between the crystal and the rigid metal plates 22 and 24 respectively. Such electrodes may be formed by brass discs and additionally serve as terminals to the ignition circuit.

The crystal 23 is held in the housing 27 by means of the spring disc 26 and is guided by means of a guiding ring 28. Insulation of the crystal and of its electrodes with respect to the housing 1 is achieved by means of the insulating holder 36. As an alternative construction, the whole housing 27 can be made of insulating material.

Because of the rotative movement of the lever about diiTerent axes when loading and when releasing, release of the hammer is automatic and the energy stored in the spring is equal with every igniting operation. Thus the energy supplied to crystal 23 is substantially the same each time it is impacted and is independent of the amount of force applied to handle 12 of the lever. During the releasing operation, the edge of the piece 11 does not move parallel to the axis of the hammer, but rather moves perpendicular to the axis of the hammer and to the direction of the spring force. Therefore, the release of the hammer by disengagement of the piece 11 and the edge 7 does not cause wear of these parts. The hammer is not released by sliding action, but rather it is suddenly released.

As soon as the impact movement has been initiated, the top edge of the metal piece 11 is positioned below the edge 29 of the hammer 5. The axle 13 is engaging the upper edge of the elongated hole 16. The torsion reset spring 31 (FIGURE 2) is fixed with its one end 32 attached to the lever 9 and with its other end 33 attached to the housing. The turning force of this spring, operating in counterclockwise direction, causes the metal piece 11 to slide along and below the edge 29 of the hammer and to snap into the groove 6 of the hammer. The ignition apparatus is then prepared for the next ignition operation.

The reset spring 31 is wound, as shown in FIGURE 2, upon a cylindrical part 35 of the lever 9. This part 35 surrounds the hole 16 of the lever.

The ignitor can be fixed to a mounting chassis or to a burner device by means of brackets 34.

Other modifications of my invention will be apparent to those skilled in the art and it is intended that the scope of my invention be as defined in the appended claims.

I claim as my invention:

1. In a piezoelectric spark ignitor having a piezoelectric crystal which is struck by a hammer to generate a high voltage and to produce a spark adapted to ignite a gas burner or the like, the improvement comprising:

first means resiliently supporting the hammer for movement in a first direction, said first means being constructed such that movement of said hammer in said first direction stresses said first means and stores energy therein,

an axle spaced from the hammer,

a movable lever mounted on said axle by means of an elongated pivot hole, said pivot hole being elongated in a direction generally normal to said first direction,

second means resiliently biasing said lever in a direction toward the hammer to thus cause said lever to engage said hammer such that rotation of said lever about said axle moves said hammer in said first direction to store energy in said first means,

and a fixed stop member located to be engaged by said lever after said lever has been rotated a given angular distance about said axle, said given angular distance being such as to align said elongated pivot hole as a portion of an are having its center of rotation generally at the point of engagement of said stop member and said lever so that further rotation of said lever is about said point of engagement and moves said lever with respect to said axle along said elongated hole and away from the hammer to release the hammer with no appreciable additional movement thereof in said first direction.

2. Spark ignitor loading and releasing apparatus, comprising:

a housing,

a piezoelectric crystal having electrodes,,

a hammer having a spring mounting said hammer on said housing adjacent a face of said crystal and adapted upon loading and subsequent release of said spring to strike said crystal face to generate a voltage,

a first pivot fixed on said housing,

a movable lever releasably pivoted about said first pivot, said lever having drive means engaging said hammer to move said hammer away from said crystal face to thus load said spring upon rotation of said lever about said first pivot,

a second pivot fixed on said housing and spaced from said first pivot and positioned such that rotation of said lever thereabout moves the drive means away from and out of engagement with said hammer,

and means associated with said lever and rendering it initially pivotable only about said first pivot, the last named means, said first and second pivots and said lever being constructed and arranged such that after a predetermined movement of said lever about said first pivot to load said spring, said second pivot is rendered effective and said first pivot ineffective so that further movement of said lever releases said hammer.

3. A spark ignitor, comprising:

a housing supporting a piezoelectric crystal,

a U-shaped spring having the bottom portion thereof fixed to said housing and arranged so that the extending blades thereof are in alignment with a face of said crystal,

a relatively large mass hammer mounted between said blades and supported thereby, said hammer having a ridge thereon,

an axle formed as part of said housing and positioned between said hammer and the bottom portion of said spring,

a lever mounted on said axle by means of an enlarged pivot hole formed in said lever, said lever including drive means adapted to engage the ridge on said hammer,

spring means biasing said lever for rotation in a first direction and biasing said lever to a first position wherein said drive means thereon engages said hammer ridge and said axle engages one edge of said enlarged hole in said lever, the unoccupied portion of said pivot hole then being directed generally toward said hammer,

a stop member formed as part of said housing and positioned a given distance from a cooperating pivot surface of said lever in order to be engaged by said pivot surface only after a given angular rotation of said lever from said first position to a second position, in a direction opposite to said first direction, said stop member and said pivot surface then providing an axis of rotation for said lever positioned such that rotation of said lever thereabout moves said lever with respect to said axle in said enlarged hole and moves said drive means out of engagement with said ridge and releases said hammer,

and actuating means operable to rotate said lever in said opposite direction to said second position to store energy in said blades, and to bring said pivot surface into engagement with said stop members, and further operable to rotate said lever about said stop member and release said hammer to strike said crystal and generate an ignition voltage.

4. A manual spark ignitor for use in igniting gas burners or the like, comprising:

a housing including a portion containing a piezoelectric crystal having an exposed face member,

a U-shaped spring having a bottom portion fixed to said housing at a position so as to align the ends of the blades thereof with said face member,

a hammer mounted between the ends of said blades, said hammer having a drive ridge formed therein, an axle formed as a part of said housing and positioned generally in alignment with said drive ridge,

a lever having an elongated pivot hole and mounted on said housing with said axle in said pivot hole,

spring means coupled to said housing and to said lever to bias said lever for rotation in a direction toward said face member, and to bias said lever for movement toward said hammer to thus cause said axle to engage an end portion of said elongated pivot hole with the remaining portion of said pivot hole being directed generally toward said hammer, I

a drive dog formed as a part of said lever and positioned to be placed in driving relation with the hammer drive ridge when said lever is in position as biased by said spring means,

a manual handle formed as part of said lever and adapted to manually rotate said lever in a direction away from said face member to thus move said hammer away from said face member to stress and store energy in said blades,

and a stop member formed as part of said housing and positioned to be engaged by a pivot surface of said lever only upon said lever being rotated a given angular distance in said direction away from said face member, said elongated pivot hole then being aligned such that it constitutes a portion of an arc whose center of rotation is the point of engagement of said lever with said stop member, said lever, the elongated hole therein said axle and said stop being so constructed and arranged that subsequent force on said handle pivots said lever about said point of engagement and moves said lever with respect to said axle along said elongated pivot hole to thus withdraw said drive dog from said drive ridge, whereupon said hammer is released to strike said face member to generate a voltage, subsequent release of said handle causing an automatic reset of said lever by virtue of said spring means.

References Cited by the Examiner UNITED STATES PATENTS Rechenbacher 4257 Ray.

Harkness 3188.1 Weber 15828 Owens 310-83 Great Britain.

MILTON O. HIRSHFIELD, Primary Examiner. I. D. MILLER, Assistant Examiner. 

1. IN A PIEZOELECTRIC SPARK IGNITOR HAVING A PIEZOELECTRIC CRYSTAL WHICH IS STRUCK BY A HAMMER TO GENERATE A HIGH VOLTAGE AND TO PRODUCE A SPARK ADAPTED TO IGNITE A GAS BURNER OR THE LIKE, THE IMPROVEMENT COMPRISING: FIRST MEANS RESILIENTLY SUPPORTING THE HAMMER FOR MOVEMENT IN A FIRST DIRECTION, SAID FIRST MEANS BEING CONSTRUCTED SUCH THAT MOVEMENT OF SAID HAMMER IN SAID FIRST DIRECTION STRESSES SAID FIRST MEANS AND STORES ENERGY THEREIN, AN AXLE SPACED FROM THE HAMMER, A MOVABLE LEVER MOUNTED ON SAID AXLE BY MEANS OF AN ELONGATED PIVOT HOLE, SAID PIVOT HOLE BEING ELONGATED IN A DIRECTION GENERALLY NORMAL TO SAID FIRST DIRECTION, SECOND MEANS RESILIENTLY BIASING SAID LEVER IN A DIRECTION TOWARD THE HAMMER TO THUS CAUSE SAID LEVER TO ENGAGE SAID HAMMER SUCH THAT ROTATION OF SAID LEVER ABOUT SAID AXLE MOVES SAID HAMMER IN SAID FIRST DIRECTION TO STORE ENERGY IN SAID FIRST MEANS, AND A FIXED STOP MEMBER LOCATED TO BE ENGAGED BY SAID LEVER AFTER SAID LEVER HAS BEEN ROTATED A GIVEN ANGULAR DISTANCE ABOUT SAID AXLE, SAID GIVEN ANGULAR DISTANCE BEING SUCH AS TO ALIGN SAID ELONGATED PIVOT HOLE AS A PORTION OF AN ARC HAVING ITS CENTER OF ROTATION GENERALLY AT THE POINT OF ENGAGEMENT OF SAID STOP MEMBER AND SAID LEVER SO THAT FURTHER ROTATION OF SAID LEVER IS ABOUT SAID POINT OF ENGAGEMENT AND MOVES SAID LEVER WITH RESPECT TO SAID AXLE ALONG SAID ELONGATED HOLE AND AWAY FROM THE HAMMER TO RELEASE THE HAMMER WITH NO APPRECIABLE ADDITIONAL MOVEMENT THEREOF IN SAID FIRST DIRECTION. 